U.S. patent number 4,552,373 [Application Number 06/595,635] was granted by the patent office on 1985-11-12 for front wheel suspension system for motorcycle or the like.
This patent grant is currently assigned to Honda Giken Kogyo Kabushiki Kaisha. Invention is credited to Yoshimi Ishikawa, Takeshi Kawaguchi, Taizo Oonishi.
United States Patent |
4,552,373 |
Kawaguchi , et al. |
November 12, 1985 |
Front wheel suspension system for motorcycle or the like
Abstract
An anti-dive device for the telescopic front fork assembly of a
motorcycle includes a contraction regulator mounted on the forward
face of the bottom case. The bottom case carries the axle for the
front wheel. Braking torque causes the movement of a member which
movement is reflected through a bell crank assembly to close the
valve in a passage connecting the two oil chambers in the front
fork assembly. A bypass passage has an orifice member which may be
moved to vary the size of a restriction in the bypass passage.
Inventors: |
Kawaguchi; Takeshi (Saitama,
JP), Ishikawa; Yoshimi (Tokyo, JP),
Oonishi; Taizo (Saitama, JP) |
Assignee: |
Honda Giken Kogyo Kabushiki
Kaisha (Tokyo, JP)
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Family
ID: |
15443539 |
Appl.
No.: |
06/595,635 |
Filed: |
March 30, 1984 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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418664 |
Sep 16, 1982 |
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Foreign Application Priority Data
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Sep 19, 1981 [JP] |
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56-148030 |
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Current U.S.
Class: |
280/276; 180/219;
188/272; 188/287; 188/318; 280/124.105; 280/5.513 |
Current CPC
Class: |
B62K
25/08 (20130101); B60G 17/08 (20130101) |
Current International
Class: |
B60G
17/08 (20060101); B60G 17/06 (20060101); B62K
25/06 (20060101); B62K 25/08 (20060101); B60G
017/08 (); B62K 025/08 () |
Field of
Search: |
;280/276,275,283,703,227
;267/34 ;188/313,272,322.1J,299,318 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1586788 |
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Feb 1970 |
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FR |
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2073680 |
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Oct 1981 |
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GB |
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Other References
Japanese Pat. Publication No. 51146/1979, published 4/24/79. .
Japanese Pat. Publication No. 29059/1977, published
7/30/77..
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Primary Examiner: Peters, Jr; Joseph F.
Assistant Examiner: Hill; Mitchell J.
Attorney, Agent or Firm: Lyon & Lyon
Parent Case Text
This application is a continuation of application Ser. No. 418,664
filed Sept. 16, 1982, now abandoned.
Claims
We claim:
1. In an anti-dive device for the telescopic front fork assembly of
a motorcycle or the like, the telescopic front fork assembly
including a bottom case having a forward wall fixed to an outer
tube telescopically receiving a fork pipe, the bottom case carrying
an axle for the front wheel, the improvement comprising, in
combination: a contraction regulator fixed on the forward wall and
having a main oil passage with a main valve therein, two spaced
openings in said forward wall communicating with said main valve in
said main oil passage, and a bell crank having a short arm moving
in response to braking torque applied to the front wheel and having
a long arm operable to close said main valve.
2. In an anti-dive device for the telescopic front fork assembly of
a motorcycle or the like, and including a caliper support bracket
and a bottom case having a forward wall fixed to an outer tube, the
bottom case carrying an axle for the front wheel, the improvement
comprising, in combination: a contraction regulator fixed on the
forward wall and having a main oil passage, two spaced openings in
said forward wall communicating with said main oil passage formed
in the contraction regulator, a valve in said passage, a bell crank
pivotally mounted to the bottom case and having a first arm coupled
with said valve and a second arm coupled with the caliper support
bracket, the caliper support bracket being able to move relative to
the case in response to braking torque applied to the front
wheel.
3. In the anti-dive device of claim 2 wherein said bell crank is
adjacent the forward wall of the bottom case.
4. In the anti-dive device of claim 2, the improvement further
comprising a tension link coupled between said second arm and the
caliper support bracket.
5. In the anti-dive device of claim 4, said bell crank and said
tension member being located adjacent the forward wall of the
bottom case.
6. In the anti-dive device of claim 2 said first arm being longer
than said second arm of said caliper.
7. In an anti-dive device for a telescopic front fork assembly of a
motorcycle including a caliper support bracket and a bottom case
fixed to an outer tube, the bottom case carrying an axle for a
front wheel and having a forward wall and a rear wall, the
improvement comprising, in combination: a contraction regulator
fixed on the forward wall, and having a main oil passage, two
spaced openings formed in the forward wall communicating with the
main oil passage formed in the contraction regulator, a valve means
located in said contraction regulator to close said main oil
passage upon application of a braking torque, a caliper mounted on
the caliper support bracket at the rear wall, a valve actuating
means mounted on the forward wall and operatively coupled at a
first end with said valve means and at a second end with the
caliper support bracket, the caliper support bracket adapted to
move through movement of said caliper in response to braking torque
applied to the front wheel whereby said valve actuating means
operated through the caliper support bracket and in turn actuates
said valve means to close said main oil passage.
Description
This invention relates to a front wheel suspension system for the
telescopic front fork of a motorcycle or the like to prevent it
from diving when the front wheel brake is applied. Typically, the
front fork includes a bottom case which carries the front wheel
axle and which is fixed to an outer tube which slidably receives a
fork pipe in telescopic relation. In such conventional
construction, the front fork is contracted when the front wheel
brake is applied. This diving action is caused by the shift of the
center of gravity, and inertia, and the front fork is fully
contracted during an abrupt braking operation.
In order to prevent the front portion of the motorcycle body fron
diving when the front wheel is braked, there have been proposed in
the prior art various types of anti-dive systems, which operate by
detecting the presence of braking torque in terms of the shift of a
member which receives the reaction to the braking force. Such shift
automatically blocks the passage of oil between chambers in the
telescopic front fork.
The present invention relates to improvements in a front wheel
suspension system of a motorcycle or the like of the type
described, and has as an important object provision of a front
wheel suspension system which enjoys a high degree of freedom for
setting the operation timing of a contraction regulator, and which
has a simple and compact construction.
Other and more detailed objects and advantages will appear
hereinafter.
In the drawings:
FIG. 1 is a sectional side elevation partly broken away, showing a
preferred embodiment of this invention.
FIG. 2 constitutes an enlargement of a portion of FIG. 1.
FIG. 3 is an end view of a casing for the contraction regulator
shown in FIGS. 1 and 2.
FIG. 4 is a side elevation thereof.
FIG. 5 is a sectional view taken substantially on the lines 5--5 as
shown in FIG. 4.
FIG. 6 is a sectional view taken substantially on the lines 6--6 as
shown on FIG. 3.
FIG. 7 is a sectional view taken substantially on the lines 7--7 as
shown on FIG. 6.
FIG. 8 is a sectional detail taken substantially on the lines 8--8
as shown on FIG. 7.
FIG. 9 is a bottom plan view taken substantially in the direction
of the lines 9--9 as shown on FIG. 4.
Referring to the drawings, the telescopic front fork 1 of a
motorcycle is constructed to include a bottom case 2 in which a
fork pipe, not shown, is slidably mounted for telescopic movement.
In the bottom portion of the bottom case 2 there is internally
mounted a front wheel axle 3 on which the motorcycle front wheel 4
is rotatably mounted by means of bearings, not shown. On both sides
of the wheel hub 5 of the front wheel 4 there are integrally
mounted two annular brake disks, not shown, and a brake caliper 6
is positioned to straddle the radially inner portions of such
annular brake disks. The brake caliper 6 is detachably mounted by
means of a bolt 8 on a caliper supporting bracket 7 which acts as a
torque receiving means.
A projection 9 formed integrally with the bottom case 2 protrudes
from the forward side thereof and carries a pivot pin 13 which
supports the L-shaped bell crank 10. The bell crank 10 has a short
arm 11 of effective length L.sub.1 and a long arm 12 of effective
length L.sub.2. A tension rod 15 is connected by pivot pin 14 to
the short arm 11 and is connected at its other end by pivot pin 16
to the caliper supporting bracket 7. The long arm 12 is bifurcated
to accept a portion of a casing 31 and carries a pin 17 fixed to
the leading ends of the bifurcated portion. The pin 17 is loosely
received in an opening 34 in the casing 31. The casing 31 is fixed
to the forward lower portion of the bottom case 2.
The magnitude of a force W to be exerted upon the leading ends of
the long arm 12 of the L-shaped bell crank 10 is reduced relative
to a force F to be exerted upon the tension rod 15 by the caliper
supporting bracket, and is expressed by the following equation:
The lower end of the seat pipe 18 together with the partition
fixture 20 is fixed to the lower end of the bottom case 2 by means
of a bolt 22. The fixture 20 is sealed at 20a with respect to the
bore 2a of the bottom case 2. In accordance with conventional
practice, a piston, not shown, is integrally formed at the upper
end of the seat pipe 18 and is hermetically sealed for sliding
movement within the fork pipe. A conventional compression coil
spring, not shown, is positioned so that the telescopic front fork
can be held in its extended state by spring force.
An oil pressure accumulating chamber 23 is defined in the annular
space between the bore 2a of the bottom case 2 and the outer
surface of the seat pipe 18 and partition fixture 20. In turn, the
chamber 24 is connected through both an opening 21 formed in the
partition fixture 20 and an opening 19 formed in the seat pipe 18.
A reservoir chamber 25 is defined by the seat pipe 18 and the
piston, not shown, at the upper end of the seat pipe. The oil
pressure, which is built up in the oil pressure accumulating
chamber 23 during the contraction stroke of the telescopic front
fork 1, is attenuated by the drag in the passage of the contraction
regulator 30. The oil under pressure passes through the
communication chamber 24 into the reservoir chamber 25 so that the
shocks and vibrations generated as a result of the motion of the
motorcycle along a roadbed are absorbed by the co-actions of the
spring force of the compression coil spring, not shown, and the
passage drag of the contraction regulator 30.
To the upper end of the partition fixture 20, moreover, there is
attached a check valve 29 which is constructed to include a seat 26
fitted on the upper end of the seat pipe 18, a sliding member 27,
and a compression coil spring 28 between the seat 26 and the
sliding member 27. At the end of the extension stroke of the
telescopic front fork 1, the working oil in the reservoir chamber
25 is directly recirculated in a low pressure drag state into the
oil pressure accumulating chamber 23 by way of the check valve
29.
The contraction regulator 30 which is located below the integral
projection 9 and fixed to the front portion of the bottom case 2
includes a casing 31, and an anti-dive piston 38 which is fitted
hermetically and slidably in a cylinder chamber 33 of the casing 31
to form an anti-dive piston valve. The contraction regulator 30
also includes a rotary type adjusting orifice element 40 which is
fitted in a bypass passage 35 comprising parts 35a, b, c, d having
an end communicating with an opening 39 formed in the piston 38. An
adjustment mechanism 46 fixes the angular position of the orifice
member 40.
The casing 31 is provided with a main passage 32 to establish
communication between the openings 51 and 52 in the bottom case 2.
The cylinder chamber 33 communicates through the opening 51 with
the oil pressure accumulating chamber 23. The bypass passage 35
provides communication between the opening 39 and the main passage
32. The adjusting orifice member 40 has a center passage 41
communicating with radial ports 42, 43 and 44 of different sizes. A
groove 45 has no communication with the same center passage 41. The
adjusting bolt 47 acts through spring 49 and against ball 48 to
cause the ball 48 partially to enter one of the ports or the groove
45, to hold the orifice member 40 in adjusted position.
Assuming that the front brake caliper 6 is not operated and
therefore no braking force is applied to the front wheel 4: Upward
shocks applied to the front wheel 4 then cause oil under pressure
in the accumulating chamber 23 to flow into the reservoir chamber
25 by way of the opening 51, main passage 32, opening 52,
communication chamber 24, and the openings 21 and 19. As a result,
the upward shocks exerted upon the front wheel 4 are absorbed by
the co-actions of the spring force of the compression coil spring,
not shown, which is positioned between the fork pipe and the upper
end piston of the seat pipe 18, and by the drag of the tortuous oil
passage thus described.
In case a downward force is exerted upon the front wheel 4, when
there is no braking force applied to the front wheel 4, the
anti-dive piston 38 is moved away from the bottom case 2 by the
force of the coil spring 53, so that the working oil under pressure
in the reservoir chamber 25 is introduced from the opening 19 via
the check valve 29 into the oil pressure accumulating chamber 23.
Since the passage drag is low in the course of this flow, the
telescopic front fork 1 can be abruptly elongated.
In a state in which the front brake caliper 6 is actuated so that
braking force is applied to the front wheel 4, a force for
effecting a counter-clockwise rotation, as viewed in FIG. 1, is
exerted upon the caliper supporting bracket 7, thereby to draw the
tension rod 15 downward. In response to this action, the L-shaped
bell crank 10 is rocked counter-clockwise about the pin 13, thereby
to bring the anti-dive piston 38 into abutment contact with the
bottom case 2 through the pin 17 against the spring force of the
coil spring 53, so that the main passage 32 is blocked. In this
particular state, by the force which is generated to compress the
front fork 1 by the shift of the center of gravity of a motorcycle
and rider and the inertial force during the braking operation, the
working oil under pressure established in the oil pressure
accumulating chamber 23 is carried into the reservoir chamber 25 by
way of the opening 51, the piston opening 39, the bypass passage
35, one of the communication passages 42, 43 and 44, the center
passage 41, the main passage 32, the opening 52, the communication
chamber 24, and the openings 21 and 19. As a result, a higher
passage drag than that developed during the operation other than
the braking operation is established to prevent the telescopic
front fork 1 from diving.
In case upward shocks are applied to the front wheel 4 when the
front fork caliper 6 is in operation to apply braking force to the
front wheel 4, the anti-dive piston 38 moves back and forth in the
chamber 33 to follow the movements of the pin 17, so that the main
passage 32 becomes open. As a result, the upward shocks are
absorbed in a similar manner to those of the usual running
operations.
Furthermore, by suitably varying the lengths of the shorter and
longer arms 11 and 12 of the L-shaped bell crank 10, thereby to set
their ratio L.sub.1 /L.sub.2 at a desired value, the force to be
exerted upon the anti-dive piston 38 can be readily selected.
Furthermore, by turning the rotary type adjusting orifice member 40
at a suitable interval of 90.degree., one of the ports 42, 43 and
44 or the groove 45 may be brought into a position to face the
bypass passage 35. Any of the passage drags of four steps can be
selectively set so that the desired anti-dive characteristics can
be established.
As described above, the present invention has been applied to a
motorcycle, but it can also be applied to an automatic tricycle
which has one front wheel and two rear wheels.
According to the present invention, the valve device, which is made
operative to block the main communication passage between the fork
pipe and bottom case, can be disposed near the bottom of the bottom
case independently of the mounting position of the brake caliper,
so that the passage of the front fork actuating oil can be
shortened to reduce the passage drag.
Having fully described our invention, it is to be understood that
we are not to be limited to the details herein set forth but that
our invention is of the full scope of the appended claims.
* * * * *